Temperature responsive sprinkler heads are well known. Such sprinker heads suffer from a number of objections. One such objection is the slow response time associated with the melting of a fusable alloy. Another problem associated with prior art sprinkler heads is the "cold sink" affect which slows down the response time of a temperature responsive disk or the like. The present invention is directed to a solution of a problem of providing a more rapid reponse sprinkler head which is extremely sensitive, reliable, and durable.